The thirty (30) day period for the filing of answer has expired. What happens now?

On the thirty-first (31st) day after service, the case goes into default. However, a defendant has an additional fifteen (15) days to open the default by filing a late answer and paying all court costs along with the filing of the answer. While defendants "may" file an answer beyond the forty-fifth (45th) day following service, such answer may be a legal nullity and void.